text: The role of PA in the cell can be divided into three categories:
  * PA is the precursor for the biosynthesis of many other lipids.
  * The physical properties of PA influence membrane curvature.
  * PA acts as a signaling lipid, recruiting cytosolic proteins to appropriate membranes (e.g., sphingosine kinase 1).
  * PA plays very important role in phototransduction in Drosophila.
  * PA is a lipid ligand that gates ion channels. See also lipid-gated ion channels.
  The first three roles are not mutually exclusive. For example, PA may be involved in vesicle formation by promoting membrane curvature and by recruiting the proteins to carry out the much more energetically unfavourable task of neck formation and pinching.